I just saw your previous reply. Is your kitchen sink along an exterior wall? It is certainly possible that your kitchen sink pipes have frozen and not others. If you have no access to the pipes, you are probably better off just waiting until it gets warmer, instead of trying to troubleshoot a problem that may be temperature based. Make sure your kitchen faucet is closed (or better yet, open just a tiny drip) so that you don't get a flood overflowing the sink when the pipe finally melts.
If your other pipes also pass through areas that might freeze, I would suggest turning all your faucets (both hot and cold) on just a bit. Even a tiny trickle should prevent them from freezing.
For the toilet, this is my approach. Take a piece of thin string and tie it around the overflow pipe to hold it in place. Place a sinker on the other end of the string. Lift the flapper and put the string under the flapper. This should allow water to drip out very slowly. When the tank level drops enough (probably every minute or two), the water will come on to refill the tank, which will maintain your flow. The sinker will keep the string from floating up when you flush the toilet, the loop around the overflow will prevent the sinker and string going down the outflow from the tank.